This invention relates to novel chemical compounds and their uses in the preparation of polymers and oligomers, and the preparation of such compounds. It also relates to polymers and oligomers prepared using such compounds, and processes for the preparation of the polymers and oligomers. More particularly, this invention relates to dendritic polymers and oligomers, of the type having at least four polymeric or oligomeric organic chains emanating from a single chemical core, each of the chains being of substantially equal length and substantially the same chemical composition. Such dendritic polymers and oligomers are referred to herein, for convenience, as dendrimers.
Dendrimers as defined above are known chemical entities. Practitioners of the chemical arts of dendrimers can recognize a core substructure to which the polymeric/oligomeric chains (xe2x80x9cdendronsxe2x80x9d) are covalently attached and from which they extend with systematic branching radially outward in a three dimensional fashion, to approximately the same extent as each other. Together, core and dendrons constitute macromolecules possessing a high degree of internal structural replication attributable to the branches. The symmetry, partial symmetry or asymmetry of the dendrimer is a partial reflection of the impact of the core. Because of the influence of both core and branches, the chemical end groups of the chains are disposed on the surface of the macromolecules. All together, core, dendrons and surface functionalities determine the properties of the polymer. Accordingly a wide variety of such materials can be prepared with different but predetermined size and shape characteristics and different but predetermined chemical surface characteristics, useful in a variety of different practical applications (chromatographic supports, catalytic supports, synthetic membranes, for example). A review of dendrimers of this type, their preparation, properties, characteristics and uses, is found in Angew. Chem. Int. Ed. Engl. (1990), 29, 138, authored by Tomalia, Donald A., Naylor, Adel M., and Goddard III, William A. The disclosure of that review is incorporated herein in its entirety.
An important feature in determining the final characteristics of such a dendrimer is the choice of core chemical entity and its properties. Some of these properties have been noted in the prior art, others have not. Among the various properties which such a core entity could beneficially possess are:
a high degree of conformational rigidity, so that each dendron may start from a point in space more or less specifically defined with respect to the starting points of other dendrons. The shape, in three dimensional space of the polyhedron, defined by the starting positions of the functional groups from which the dendrons eventually protrude, is in this way a characteristic property of a core. If the dendrons are flexible but the dendrimer is to have some substantial element of controlled shape, that shape is largely dictated by the rigid core;
a large number of identical functionalities to which the dendrons may be attached. This will reduce the number of generations before the dendrimer surface assumes an essential spherical shape covered by a large number of surface reactive groups;
core functionalities sterically well separated, to reduce the likelihood of intramolecular branch defects; and
an overall low symmetry and chirality, so that in cases where the dendrimer is to be used in a natural biological environment, the dendrimer will more closely mimic such environment.
Many different compounds have been proposed in the prior art, for use as the core entity of such dendrimers. The aforementioned article of Tomalia et. al. discloses ammonia, amines, linear polyethyleneimines, polyethylene glycols and a number of others. More complex cores, including chiral cores, have also been used. The range of possible candidates is very broad. Jason M. Rohde and Jon R. Parquette, in xe2x80x9cSynthesis of dendrimers containing 2,5-anhydro-D-mannitol as chiral tetra-functional central core with C2 symmetryxe2x80x9d, Tetrahedron Letters (1998), 39, 9161 disclose the use of 1,3,4,6-tetra-O-(4-hydroxybenzoyl)-2,5-anhydro-D-mannitol as core for a dendrimer. Whilst an advance over small molecular cores, this compound still exhibits too much rotatidnal flexibility in its bonds and is thus capable of assuming too many conformations. The desirability of providing more rigid dendrimer cores, to obtain more extensive conformational order in the polymers, has recently been acknowledged by Weintraub et. al. in xe2x80x9cSynthesis and chiroptical properties of amphiphilic dendrimers based on 2,3-dihydroxybenzyl alcoholxe2x80x9d, Tetrahedron (2001), 57, 9393.
It is an object of the present invention to provide novel chemical entities useful as core entities in the preparation of dendrimers.
It is a further object of the invention to provide novel dendrimers based on the novel chemical entities.
The present invention, from one aspect provides novel chemical entities useful as core entities in dendrimers and corresponding to the following general chemical structure Q. 
Wherein:
at least one of the W and W1 groups on a given phenyl ring is independently an electron-donating functionality and the other is independently selected from hydrogen and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving either Z or an adjacent substituent R;
Z is either hydrogen or together with an adjacent substituent W or W1, forms a fused rigid ring as aforesaid;
R1 and R2 are independently selected from hydrogen, a non-interfering chemical group, and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving an adjacent substituent W on the same phenyl ring; or together represent a first bridge joining the respective carbon atoms to which each R1 and R2 is attached, said first bridge being selected from direct bond and xe2x80x94(CH2)xe2x80x94;
T-butyl, chloro, bromo, iodo, alkylthio, halogen substituted methyl, lower alkoxy substituted methyl, lower alkylthio substituted methyl.
R3 is selected from hydrogen, a non-interfering chemical group and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving an adjacent substituent W1, or R3 forms a second bridge with R4, said bridge joining the respective carbon atoms to which each R3 and R4 is attached and said second bridge being selected from direct bond, xe2x80x94(Cxe2x95x90O)xe2x80x94, xe2x80x94(CH2)xe2x80x94 and xe2x80x94(CHOH)xe2x80x94;
R4 is either hydrogen or together with R3, forms the aforesaid second bridge, with the proviso that R1 and R2 do not form a bridge when R3 and R4 form a bridge;
R5 is either hydrogen or together with R6 forms a third bridge, said bridge joining the respective carbon atoms to which each R5 and R6 is attached and said third bridge being selected from, xe2x80x94(Cxe2x95x90O), xe2x80x94(CH2)xe2x80x94 and xe2x80x94(CHOH)xe2x80x94;
R6 is selected from hydrogen, a non-interfering chemical group and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving an adjacent substituent W1, or together with R5 forms the aforesaid third bridge;
R7 is selected from hydrogen, a non-interfering chemical group and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving an adjacent substituent W1;
R8 is selected from hydrogen, a non-interfering chemical group and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving an adjacent substituent W; and
R9 is selected from hydrogen, a non-interfering chemical group and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving an adjacent substituent W1.
Such a chemical entity provides a number of features, which in combination lead to the formation of highly desirable dendrimers based thereon. One such feature is the substantial orientational rigidity of aromatic rings with respect to the central indane (benzocyclopentane) moiety. The indane system is itself capable of no internal rotation and only slight flexing. Each aryl substituent on the five membered ring can effectively only rotate around that axis established by the specific carbon-carbon bond linking it directly to the central carbocycle.
The term xe2x80x9celectron donating functionalityxe2x80x9d is used in this specification with more quantitative distinction than is the common understanding. This quantitative designation is based on the scale of specialized Hammett constants called "sgr"p+ values established by Herbert C. Brown and Y. Okamoto in xe2x80x9cElectrophilic Substitution Constantsxe2x80x9d, J. Am. Chem. Soc., (1958), 80, 4979. By the term, xe2x80x9celectron donating functionalityxe2x80x9d as the term is used herein is meant a group having "sgr"p+ less than 0. Speaking qualitatively, such substituents activate their parent rings towards electrophilic aromatic substitution and direct this substitution to positions ortho and para to themselves, often with a significant preference for para substitution. They prominently activate and accelerate the electrophilic aromatic substitution of their parent rings.
Preferred electron-donating groups are hydroxyl, methoxyl, lower alkoxyl, nitrogen substituted lower alkoxyl, carboxyl substituted lower alkoxyl, acylated amino and sufonyl substituted amino.
xe2x80x9cNon-interfering substituentsxe2x80x9d as the term is used herein means those that interfere neither with the course of chemical synthesis of the core molecules, nor in the course of the chain extension to prepare dendrimers from the core molecules. The choice of groups W or W1 affects whether a particular group should be regarded as a non-interfering substituent. As a general guide, when W or W1 has a "sgr"p+ value of from about 0.0 to xe2x88x920.5, a non-interfering substituent is one which has "sgr"p+ greater than +0.2. When W or W1 has "sgr"p+ less than xe2x88x920.5, a non-interfering substituent is one which has "sgr"p+ greater than xe2x88x920.3.
Fused rigid mono or polycyclic carbocyclic or N-heterocyclic rings are those chemical ring systems which contribute to the rigidity of the resulting core entity according to the invention. Preferred ring systems are ring systems which are essentially rigid with any attached substituents being essentially rigid and with no geometric or chiral centres introduced by the fusion of the two particular carbons of the ring system and the exactly corresponding two particular ring carbons of Q. Examples include aromatic monocyclic or polycyclic rings such as naphthyls, anthracyls, phenanthryls or the like; alicyclic rings such as cyclobutyls, cyclopentyls or cyclohexyls; N-heterocyclic rings such as pyridyl, piperidyl, imidazolyl or the like; the heterocyclic group should be chosen so as not to interfere with the subsequent use of the core entities in the dendrimer formation or the ease of chemical preparation of the core entities themselves. Sulfur or oxygen heterocycles are generally unsuitable. Preferred such fused rings are aromatic rings on account of their rigidity.
Another aspect of the invention is novel chemical compounds which can be reacted to form the dendrimer core entities according to the invention, namely indenone compounds of the general formula: 
wherein:
W represents an electron-donating functionality; and
X and Y are different from one another and represent hydrogen or an electron-donating functionality,
optionally, each of the other positions on the phenyl rings are substituted with non-interfering chemical groups.
A further aspect of the invention is a dendrimer comprising the core entity according to the invention, and organic chains outwardly emanating from said core entity. Dendrimers have self-limiting growth characteristics. The defect level becomes progressively higher and divergence from branch ideality becomes substantial at least by generation nine. The preferred dendrimers produced from cores of the invention are monodisperse, with branching ideality of 95% or greater, and with between zero and nine repetitions of the monomeric branching motif. In preferred embodiments of this aspect, the organic chains can be selected from the group consisting of:
Oxe2x80x94[CH2xe2x80x94C6H3-2,3-(CH2xe2x80x94C6H3-2,3-[CH2xe2x80x94C6H3-2,3-(CH2xe2x80x94C6H4-4-COOH)2]2)2],
Oxe2x80x94[CH2xe2x80x94C6H3-3,5-(CH2xe2x80x94C6H3-3,5-[CH2xe2x80x94C6H3-3,5-(CH2xe2x80x94C6H4-4-COOH)2]2)2],
Oxe2x80x94[CH2CH2N(CH2CH2CONH CH2CH2N[CH2CH2CONHCH2CH2NH2]2)2],
Oxe2x80x94[CH2CONHCH2CH2N(CH2CH2CONHCH2CH2N[CH2CH2CONHxe2x80x94CH2CH2NH2]2)2],
Oxe2x80x94[CH2CH2N(CH2CH2CONHCH2CH2N[CH2CH2CONH CH2CH2N(CH2CH2COxe2x80x94NHCH2CH2NH2)2]2)2], and
Oxe2x80x94[CH2CONHCH2CH2N(CH2CH2CONHCH2CH2N[CH2CH2CONHxe2x80x94CH2CH2N(CH2CH2CONHCH2CH2NH2)2]2)2].
In more preferred embodiments, the organic chains may be of substantially equal length or of substantially the same chemical composition.
xe2x80x9cLower alkylsxe2x80x9d as the term is used in this specification designates alkyls from C1 to C6.